/*
 Copyright 2011 Software Freedom Conservancy.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

package org.openqa.selenium.remote.service;

import com.google.common.base.Throwables;

import org.openqa.selenium.WebDriverException;
import org.openqa.selenium.remote.Command;
import org.openqa.selenium.remote.DriverCommand;
import org.openqa.selenium.remote.HttpCommandExecutor;
import org.openqa.selenium.remote.Response;

import java.io.IOException;
import java.net.ConnectException;

/**
 * A specialized {@link HttpCommandExecutor} that will use a {@link DriverService} that lives
 * and dies with a single WebDriver session. The service will be restarted upon each new session
 * request and shutdown after each quit command.
 */
public class DriverCommandExecutor extends HttpCommandExecutor {

  private final DriverService service;

  /**
   * Creates a new DriverCommandExecutor which will communicate with the driver as configured
   * by the given {@code service}.
   * 
   * @param service The DriverService to send commands to.
   */
  public DriverCommandExecutor(DriverService service) {
    super(service.getUrl());
    this.service = service;
  }

  /**
   * Sends the {@code command} to the driver server for execution. The server will be started
   * if requesting a new session. Likewise, if terminating a session, the server will be shutdown
   * once a response is received.
   * 
   * @param command The command to execute.
   * @return The command response.
   * @throws IOException If an I/O error occurs while sending the command.
   */
  @Override
  public Response execute(Command command) throws IOException {
    if (DriverCommand.NEW_SESSION.equals(command.getName())) {
      service.start();
    }

    try {
      return super.execute(command);
    } catch (Throwable t) {
      Throwable rootCause = Throwables.getRootCause(t);
      if (rootCause instanceof ConnectException &&
          "Connection refused".equals(rootCause.getMessage()) &&
          !service.isRunning()) {
        throw new WebDriverException("The driver server has unexpectedly died!", t);
      }
      Throwables.propagateIfPossible(t);
      throw new WebDriverException(t);
    } finally {
      if (DriverCommand.QUIT.equals(command.getName())) {
        service.stop();
      }
    }
  }
}
